1. Field of the Invention
The present invention relates to a ratchet screwdriver, more particularly to a ratchet screwdriver which has an orientation regulator that is turnable between first and second angular positions so as to permit clockwise and counterclockwise driving rotations of a drive shaft.
2. Description of the Related Art
U.S. Pat. No. 6,151,994 discloses a ratchet screwdriver that includes a handle defining a ratchet shaft receiving hole therethrough, and a ratchet shaft disposed therein. The ratchet shaft has a ratchet wheel mounted securely between first and second end portions. An engaging unit is interposed between the ratchet shaft and a drive shaft inserted in the first or second end portion to prevent relative axial displacement and permit co-rotation therebetween. A ratchet housing includes a coupling portion sleeved on the ratchet shaft and coupled to the handle for co-rotation therewith, a wheel confining portion defining a cavity for enclosing the ratchet wheel, and a shoulder between the coupling and wheel confining portions. The wheel confining portion is formed with a pawl-retaining groove in communication with the cavity to receive a pawl member which is mounted pivotally on the shoulder and which extends radially into the cavity. A biasing member biases the pawl member to engage the ratchet wheel such that when the handle is driven in a counterclockwise direction, the ratchet and drive shafts correspondingly rotate in the counterclockwise direction.
One disadvantage of the aforesaid ratchet screwdriver resides in that when it is desired to rotate the drive shaft in a clockwise direction, the handle is turned 180 degrees along a radial line to reverse positions of the first and second end portions of the ratchet shaft, and the drive shaft is disassembled and then re-assembled to a selected one of the first and second end portions of the ratchet shaft to permit driving rotation of the handle in the clockwise direction.
Therefore the object of the present invention is to provide a ratchet screwdriver which can solve the aforementioned problem.
Accordingly, the ratchet screwdriver of the present invention includes a drive shaft, a shaft-mounting seat, an elongated handle, and a ratchet assembly. The drive shaft defines a first axis, and has a coupling section, and an operating section which extends axially from the coupling section and which defines a tool-retaining hole with a non-circular cross-section. The shaft-mounting seat includes a peripheral wall that defines a shaft-receiving space to receive the coupling section of the drive shaft therein, and that has front and rear ends, and an upper wall portion formed with two spaced apart opposing spring-retaining recesses in spatial communication with the shaft-receiving space, and two spaced apart opposing pawl-limiting through-holes which are disposed between the spring-retaining recesses. Each of the pawl-limiting through-holes is confined by a hole-confining wall. The shaft-mounting seat further includes front and rear end flanges that extend inwardly and respectively from the front and rear ends of the peripheral wall in a transverse direction relative to the peripheral wall. The coupling section of the drive shaft extends through the front end flange, the shaft-receiving space, and the rear end flange. The handle is securely connected to the rear end of the shaft-mounting seat. The ratchet assembly includes a ratchet wheel, opposing left and right pawls, opposing left and right biasing members, a regulator in the form of a tubular sleeve, and a positioning unit. The ratchet wheel is disposed around and is connected securely to the coupling section of the drive shaft for co-rotation therewith in the shaft-receiving space, and has a plurality of engaging teeth formed circumferentially therearound. Each of the left and right pawls is disposed in the shaft-receiving space among the drive shaft, a respective one of the spring-retaining recesses, and a respective one of the pawl-limiting through-holes. Each of the left and right pawls has two opposite pivot ends respectively pivoted to the front and rear end flanges, a teeth-engaging portion between the pivot ends, and an actuating portion which projects from the teeth-engaging portion through a respective one of the pawl-limiting through-holes. The pivot ends of each of the left and right pawls are limitedly turnable relative to the shaft-mounting seat about a second axis that is parallel to the first axis and so as to be turnable about the first axis together with the shaft-mounting seat. The left and right biasing members are disposed in the spring-retaining recesses, respectively, for urging the teeth-engaging portions of the left and right pawls to releasably mesh with the engaging teeth of the ratchet wheel. The tubular sleeve is sleeved rotatably around the peripheral wall of the shaft-mounting seat, and has an inner wall that is formed with a sector-shaped recess defined by a recess-confining wall. The tubular sleeve is turnable about the first axis relative to the shaft-mounting seat between a first angular position, where the actuating portion of the left pawl is pushed by the recess-confining wall of the tubular sleeve against biasing action of the left biasing member so as to turn about the second axis to abut against the hole-confining wall of the respective one of the pawl-limiting through-holes and so as to permit the teeth-engaging portion of the left pawl to disengage from the engaging teeth of the ratchet wheel, and where the teeth-engaging portion of the right pawl engages the teeth of the ratchet wheel, and a second angular position opposite to the first angular position, where the actuating portion of the right pawl is pushed by the recess-confining wall of the tubular sleeve against biasing action of the right biasing member so as to turn about the second axis to abut against the hole-confining wall of the other one of the pawl-limiting through-holes and so as to permit the teeth-engaging portion of the right pawl to disengage from the engaging teeth of the ratchet wheel, and where the teeth-engaging portion of the left pawl engages the engaging teeth of the ratchet wheel. The positioning unit is disposed between the shaft-mounting seat and the tubular sleeve for releasably engaging the shaft-mounting seat and the tubular sleeve once the tubular sleeve is moved to the first and second angular positions. As such, when the tubular sleeve is moved to the first angular position, rotation of the handle in a clockwise direction results in synchronous rotation of the shaft-mounting seat and the drive shaft in the clockwise direction, and rotation of the handle in a counterclockwise direction results in idle rotation of the handle relative to the drive shaft. Accordingly, when the tubular sleeve is moved to the second angular position, rotation of the handle in the counterclockwise direction results in synchronous rotation of the shaft-mounting seat and the drive shaft in the counterclockwise direction, and rotation of the handle in the clockwise direction results in idle rotation of the handle relative to the drive shaft.